How do I open a DWG file. in sketchup ..?

You may need to minimize your .dwg file size before importing to SU. Try these steps: 1. "Save As" your Autocad drawing and delete unnecessary entities you don't need. If you only need the floor plan for example, then delete the others. 2. Put all the objects or entities in a single layer preferably in Layer0. 3. Purge all unused layers, linetypes, etc. and save the file as .dwg normally. 4. Open Sketchup, click File-->>Open and locate your saved dwg. Don't forget to click the options button on the right pane and select the correct units for consistency. 5. Click Open button to import your ACAD file to SU.